抗负载突变的孤岛检测方法

The islanding-detection method of resistance to load mutation

并网逆变器运行过程中可能出现孤岛运行状态,孤岛运行会威胁到电网维修人员的安全,在重合闸时可能会对用电设备造成损坏,故光伏并网系统应具有一种特殊的保护功能——孤岛保护.传统的孤岛检测方法是采用过压/欠压检测或频率变化率检测,或二者相结合的方法,然而这种被动式检测方法只能够检测光伏并网系统输出功率和负载功率不匹配时的孤岛现象,当功率匹配时,却无法检测出来.因此本文提出一种抗负载突变的相位变化检测方法,该方法能在频率的变化改变缓慢时,将相位变化置零,并结合传统孤岛检测方法,既有传统检测方法的优势:反应速度快,不影响电网的电能质量;又能检测出输出功率与负载功率匹配的情况下产生的孤岛现象.在MATLAB/SIMULINK下分别对传统方法和新的方法进行了系统的仿真,仿真试验证明了所提出方法的正确性,避免了传统方法因负载突变造成的误判,实现了系统的无盲区检测.

Grid invert operation may present island running state during the process,and island operation would threaten the safety of power grid maintenance personnel and might damage electric equipment when in reclosing,so the photovoltaic grid system should have a special protection function——-island protection.The traditional islanding-detection method adopts over-voltage/under-voltage detection and frequency variation detection,or the combination of the two methods,but this method can only detect the island phenomenon when the output power of photovoltaic grid system and the load power does not match.When power matching,this method can not detect.Therefore,a phase change detection method with the resistance to load mutation is proposed in this paper:when frequency changes is slow,phase change is set to zero.This method combine the traditional islanding-detection method,which not only have the advantage of traditional detection method,quick response and no affecting grid power quality,but also can detect the case of islanding when the output power of photovoltaic grid system and the load power matches.The traditional method and the proposed method were simulated in the MATLAB/SIMULINK,respectively.The simulation results have proved the correctness of the proposed method,and it can avoid the traditional method for load mutation of justice for islanding mistakes,and realize the system without blind spot detection.